Operating Instructions

Communication via RS485
5.5 Communication via BACnet MS/TP - only CU230P-2 HVAC / BT
Fieldbuses
160 Function Manual, 04/2018, FW V4.7 SP10, A5E34229197B AE
5.5.3
Acyclic communication (general parameter access) via BACnet
Acyclic communication or general parameter access is realized via BACnet objects DS47IN
and DS47OUT.
Acyclic communication uses the octet string value objects OSV0 and OSV1.
Instance
ID
Object name
Description
Access
type
OSV0
DS47IN
Maximum length 242, of which two bytes header, 240
bytes user data
W
OSV1 DS47OUT R
The OSV are structured as follows:
Function
Code
Request length
User data
2F (1 Byte)
(1 byte)
Maximum 240 bytes
Write parameter request with OSV0 and read with OSV1
To read parameter r0002 write the following values into the present value window of OSV0
Table 5- 33 Write parameter request via OSV0
Byte
Description
2F h
0A h
80 h
01 h
01 h
01 h
10 h
01 h
0002 h
0000 h
1
2
3
4
5
6
7
8
9,10
11,12
Function code 2F h (47),
Request length 10 bytes (0A h)
Request reference = 80 h
Request identifier = 1 h
DO-Id = 1
Number of parameters = 1
Attribute
Number of elements = 1
Parameter number = 2
Subindex = 0
If the request was successfully processed, then you can read out the response precisely
once from the present value window of the OSV1:
Table 5- 34 Read parameter content via OSV1
Byte
Description
2F h
08 h
80 h
01 h
01 h
01 h
10 h
01 h
001F h
1
2
3
4
5
6
7
8
9,10
Function code 2F h (47)
Response length 8 bytes
Request reference = 80 h
Request identifier = 1 h
DO-Id = 1
Number of parameters = 1
Format
Number of elements = 1
Parameter value 1F h = 31